Method of making fasteners



Dec. 12,1939. pRNTlcE 2,183,169

METHOD OF MAKING FASTENERS Filed Nov. 5, 1938 Patented Dec. 12,1939

UNITED. STATES.

"PATENT OFFICE 7 2,183,169 METHOD OF MAKING FASTENERS George E.Prentice, Berlin, Conn., assignor to The G. E. Prentice ManufacturingCompany, New Britain, Conn., a. corporation of Connecticut ApplicationNovember 5, 1938, Serial No. 238,949

3 Claims.

This invention pertains to slide fasteners and relates more particularlyto a method of making such fasteners. In Patent No. 1,796,395, grantedto G.'E. Prentice, March 17, 1931, there is disclosed a type of fastenerin which the fastener elements of each of the opposed series areconstituted by the successive turns of an open coiled helix of wire. Asdisclosed in this patent, the fastener elements of both series arealike, being turns of simple cylindrical coils, but in Patent .No.1,724,311, granted to G. E. Prentice on August 13, 1929, an improvedconstruction is disclosed wherein the turns of the coil forming at leastone of the series of fastener elements are so deformed or bent from truehelical curvature as to constitute hook-like parts operative to engagethe turns of the opposite coil with a positive grip. Heretofore inmaking the deformed coil it has been thought necessary first to form asimple cylindrical coil from plain wire by usual wire coiling operationsand then to deform the turns of the coil by a swedging operation. Thus,two sep- 1 arate operations, involving two handlings of the material,were requisite, and unless the swedging operation were carefullyperformed, the resultant fastener elements might not be uniformly spacedor properly aligned so that a defective fastener would result.

The principal object of the present invention is to provide an improvedmethod of making such fasteners, in particular a deformed helical coilfor use in such fasteners, such that the operation is simplified,cheapened and more rapidly performed than has previously been possible,while 1 at the same time insuring uniform results. In

accordance with this novel method, a length of plain wire is firstcrimped transversely to form a series of undulations all in the sameplane and of uniform length and depth, and thereafter this crimped wireis coiled to form an open helical coil. In thus crimping the wire, it isdesirable to make the depth of each undulation substantially equal tothe pitch of the desired coil, and

also to make the length of the undulation to be an aliquot part of thecircumference of the completedcoil.

- A convenient way of performing the above operation is to pass the wirebetween a pair of transversely toothed or corrugated rolls whichpreferably also constitute feed rolls for advancing the wire, thencausing the wire with its undulations formed by the action of the teethof the rolls to move along a path in which it is confined so that it cannot bend transversely, and then delivering the crimped wire directly toa coiling device, for example a tapered and threaded mandrel disposedwithin a hollow cylindrical die, the pitch of the mandrel being that ofthe desired coil and the internal diameter of the die being the externaldiameter of the desired coil. The teeth of the rolls are of such shape,depth and circumferential length as to form. undulations of the desireddepth and length, and by the use of this arrangement it is possible todeliver the plain wire-continuously and without interruption and to havethe completed coil dis charged from the die ready to be cut to desiredlength for use.

' In the accompanying drawing wherein the steps of the improved methodare illustrated diagrammatically, and by reference to mechanism forcarrying them into effect:

Fig. 1 is a side elevation partly in vertical section illustrating asimple apparatus useful in performing the improved method;

I Fig.2 is a horizontal section substantially on the line 2-2 of 'Fig.1;

Fig.2 is a fragmentary section 2'-2 of Fig. 2;

Fig. 3 is a fragmentary side elevation to larger scale illustrating theappearance of the completed coil resulting from the practice of theimproved method; and

Fig. 4 is a fragmentary front elevation showing a slide fastenercomprising a deformed coil such 'as results from the practice of thepresent method.

Referring to the drawing, the numeral l designates the frame of amachine useful in the performance of the improved method. This frame onthe line of which is driven by suitable drive means not shown. On theseshafts are mounted rolls 4 and 5, respectively, these rolls havingtoothed or corrugated edges, theteeth preferably being of undular orapproximately sinusoidal form. The teeth of the, two rolls mesh witheach other after the manner of gear teeth but with a clearancesubstantially equalling the diameter of the wire to be coiled.

The circumferential length of each of the teeth 6, as indicated at 1,preferably is an aliquot part of the circumference of the coil to beformed, in the present instance being one-quarter of the circumferenceof the completed coil. Further-v more, the depth of each of the teeth 6,as indi catedat 8 in Fig. 1, is preferably substantially equal to thepitch of the coil which is to b formed.

provides bearings for shafts 2 and 3, one or both 'in the form of acompleted coil 20.

of the arrows shown in Fig. 1 and thus advance the wire W to the left asviewed in said figure. The action of the rolls is to crimp the wirewhich passes between them so as to form undulations in the wire, alldisposed in substantially the same plane, this being the plane of thepaper as seen in the drawing. Immediately after leav-. ing the rolls,the crimped wire enters a guide passage 9 in a housing In which extendsfrom adjacent to the delivery point of the rolls to thecoiling die. Theguideway 9 is of a horizontal width substantially equal to the diameterof the wire and of a vertical depth equal to the depth of theundulations or crimps formed in the wire, that is to say, as here shown,equal to the pitch of the coil to be formed. The housing I0 issubstantially rigid and so confines the crimped wire as it moves fromthe rolls toward the die that it cannot bend or deflect out of theproper path. The frame of the machine supports a bracket ll having avertical guideway for the reception of a vertically slidable die memberI2. This die member may be adjusted vertically and when properlypositioned is retained in position by means of a set screw [3 orequivalent means. The die member i2 is provided with an elongatevertical bore H of a diameter substantially equal to that of the coilwhich is to be formed. The axis of the bore I4 is slightly offset fromthe guide passage 9 in the housing i0, although its axis is vertical andthus parallel to and very closely adjacent to the plane of thecorrugations in the wire as the latter advances through the passage 9.

Directly above the die member I! the frame of the machine is providedwith a bracket it having a vertical internally screw-threaded borealigned with the die passage l4 and which receives a threaded portion 16of a mandrel-asunporting stem l'l having a head at its upper end bymeans of which it may be turned for vertical adjustment. The lower partof this stem I1 is shaped to provide a downwardly tapering mandrel I8having an external screw thread of a pitch equalling the desiredpitch'of the coil to be formed. The mandrel l8 tapers downwardly andpreferably terminates in a point l9 adjacent to the lower end of the diecavity or passage M.

In the operation of the device the wire W is advanced between the rolls4 and 5, the latter preferably acting as feed rolls for the wire and atthe same time forming transverse crimps or undulations therein. Thecrimped wire advances through the passage 9 in which it is closelyconfined, and its advancing end enters through av suitable opening inthe wall of the die passage or cavity l4 and is forcibly advancedagainst the forming mandrel l8. Due to the slight offset of the axis ofthis mandrel with respect to the delivery end of the passage 9, theadvancing end of the wire strikes the circumferential surface of themandrel more or less tangentially and, being confined between thecentral core of the mandrel, the wall of the die passage I4 and thefaces of adjacent turns of the screw thread on the mandrel, theadvancing wire is compelled to take a helical course, gradually passingdown axially along the mandrel l8 and eventually escaping from the lowerend of the die passage ll This coil has the characteristics of the coildisclosed in the Prentice Patent No. 1,724,311 above referred to, theundulations formed in the wire as it advances being preserved andembodied in the helical coil. By reason of the definite relation betweenthe lengths and depths of the undulations formed in the wire and thediameter and as shown in Fig. 1, a reciprocating cutter C,

sliding'in a guide G is disposed to move in a horizontal path just belowthe lower end of the die. This cutter may be actuated by any suitablemeans, for example a cam, not shown, moving in timed relation to therolls 4 and 5.

In Fig. 4 a fastener of the general type to which the invention relatesis diagrammatically illustrated, such fastener comprising the tapes orstringers 2| and 22 and the slider 23. To the tape 2| is secured adeformed coil 20 such as results from the practice of the method abovedescribed, while the opposite stringer 22 is provided with a coil 20which may be a plain helical coil if desired.

While one desirable form of apparatus useful in performing the methodhas herein been described, it is to be understood that the invention isnot necessarily limited to the use of such apparatus but that theimproved method may be carried out by other means, includinghandactuated implements if desired.

I claim:

1. That method of making fasteners of the kind in which one series atleast of fastener elements consists of consecutive convolutions of anopen coiled spring which comprises as steps transversely crimping alength of wire to form a series of uniformly spaced undulations therein.the undulations being disposed in the same plane, each undulation beingof a depth which equals the pitch of the desired coil and of a lengthwhich is an aliquot part of the circumference of the desired coil, and,so confining it as to prevent change in the plane, length or depth ofits undulations, advancing the crimped wire longitudinally intotangential contact with a concavely curved rigid cylindrical surfacewhose axis is substantially parallel to the plane of said undulations,and deflecting the advancing wire axially of said surface thereby tocause it to follow a helical path and assume the form of the desiredcoil. I

2. That method of making fasteners of the kin in which one series atleast of fastener elements consists of consecutive convolutions of anopen coiled spring which comprises as steps advancing a length of wirebetween crimping rolls having transverse teeth operative to formundulations of uniform length and depth in the wire, so advancing thecrimped wire, while confining it in such a way as to maintain unchangedthe depth and'length of its undulations as to cause its advancing end tocontact a stationary, concavecylindrically curved surface and to followa helical path longitudinally of said surface, the radius of saidsurface being such that the circumference of the resultant wire helix issubstantially four times the length of each undulation.

3. That-method of making wire coils of substantially any desired lengthfor use in fasteners of the kind in which one series at least offastener elements consists of consecutive convolutions of an open coiledspring which comprises troducing the advancing end of the crimped wire,into an annular elongate rigid-walled chamber and causing said end tofollow a helical path of definite pitch in moving toward the exit end ofsaid chamber thereby to term an open coiled helix.

GEORGE E. PRENTICE.

